Windows 10 not showing in grub, but can be selected via UEFI bios

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1

I recently had to swap out a motherboard and for some reason now I can’t find windows as an option in grub. I think I have two EFI partitions for some reason…

sudo parted -l

Number  Start   End     Size    File system     Name                          Flags
 1      1049kB  524MB   523MB   ntfs            Basic data partition          hidden, diag
 2      524MB   629MB   105MB   fat32           EFI system partition          boot, esp
 3      629MB   646MB   16.8MB                  Microsoft reserved partition  msftres
 4      646MB   69.4GB  68.7GB  ntfs            Basic data partition          msftdata
 5      69.4GB  69.9GB  537MB   fat32                                         msftdata
 6      69.9GB  72.0GB  2147MB  linux-swap(v1)                                swap
 7      72.0GB  256GB   184GB   ext4

lsblk

sda 8:0 0 238.5G 0 disk
├─sda1 8:1 0 499M 0 part
├─sda2 8:2 0 100M 0 part
├─sda3 8:3 0 16M 0 part
├─sda4 8:4 0 64G 0 part
├─sda5 8:5 0 512M 0 part /boot/efi
├─sda6 8:6 0 2G 0 part [SWAP]
└─sda7 8:7 0 171.4G 0 part /

Any ideas on how to proceed?

2

Have you checked if OS prober is activated in your /etc/default/grub?
There must something like

GRUB_DISABLE_OS_PROBER=false

If yes, then just run

sudo update-grub

and reboot.

1 Like
3

I can confirm that it does grab does contain OS_PROBER=false, and update-grub did not find anything. Running os-prober by itself also doesn’t seem to do anything.

4

Try echo GRUB_DISABLE_OS_PROBER=false | sudo tee -a /etc/default/grub && sudo update-grub to regenerate the grub file

5

whats is output of sudo update-grub

6 
echo GRUB_DISABLE_OS_PROBER=false | sudo tee -a /etc/default/grub && sudo update-grub
GRUB_DISABLE_OS_PROBER=false
Generating grub configuration file ...
Found theme: /usr/share/grub/themes/manjaro/theme.txt
Found linux image: /boot/vmlinuz-5.10-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.10-x86_64.img
Found initrd fallback image: /boot/initramfs-5.10-x86_64-fallback.img
Found linux image: /boot/vmlinuz-5.4-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.4-x86_64.img
Found initrd fallback image: /boot/initramfs-5.4-x86_64-fallback.img
Warning: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
Found memtest86+ image: /boot/memtest86+/memtest.bin
done

Doesn’t seem to show much as far as I can tell…

7

Now how does it display when reboot?

8

No change. No boot entry for Windows in grub. I need to manually select it via the UEFI boot device to get to windows.

9

I think your Manjaro is installed in BIOS mode. If Windows is installed in UEFI mode is not going to be added to the grub (grub does not support this).

To confirm this run this commad:

efibootmgr -v

But if your Manjaro is in BIOS mode, you don’t need to search for anything else. It’s just that.
Do you get some output or just an error?

Also os-prober (run by update-grub process) is quite verbose in the logs. Execute it:

sudo os-prober

and then check the logs. Maybe you can figure out from them why is not adding your Windows.

journalctl -b -xe
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